When you think "PC gaming," you probably think about games you play with a mouse and keyboard--everything from Grim Fandango to World of Warcraft. But savvy gamers know that the hardware that powers their PCs isn't so different from the hardware found in an everyday game console. Thanks to the work of legions of troglodytic emulator-developing heroes over the past 15 years or so, your PC can run almost any game from most of the dedicated game consoles taking up space in your living room (or your attic)--and we'll show you how.

The Nintendo DSi is but one of the consoles we'll cover in this how-to.With an emulator app, your PC can translate on-the-fly the commands that a game console processor receives--whether that console is a classic NES or a new Nintendo Wii. Though they're not quite as efficient as running the software directly would be (your PC is probably more powerful than an Xbox 360, but it's not powerful enough to emulate Gears of War), emulators have grown by leaps and bounds, and continue to do so. Any Dell you might buy off-the-shelf tomorrow is most likely able to run the PS2's entire library.

Read on for an explanation of a few commonly used emulation terms, or click on our console-specific how-to articles on the right-hand side to learn how to set up the emulator of your choice.

Obligatory disclaimer: Emulating game consoles is a somewhat dicey topic because it could enable you to download and play games you don't legally own. This series of articles is intended to show you how to get your PC to run these emulators, but we assume that you intend to play your own games (either from the original disc/cartridge or from a backup file), and we can't tell you where to find illegally copied game files or BIOS images.

Emulation Cheat Sheet

Before you jump head-first into the wild world of game console emulation, there are a few key terms you should know.

BIOS images are the same thing in a console that they are in your PC: tiny, unchangeable bits of software that sat on the original console's motherboard, variously providing the security boot-up checks (such as on the Neo-Geo) or the interface for playing music CDs (as on the Sega Saturn). They're more commonly used in newer, non-Nintendo consoles, and often are mandatory. The copyright status of these is a sticky subject, and they're never distributed alongside the emulators themselves. The least troublesome way to obtain them is by consulting the emulator's documentation for the BIOS's filename (for example, a common PlayStation BIOS is called SCPH1001.bin) and then googling that filename.

Sonic the Hedgehog is a key figure in the world of emulation.Frameskip is a feature that speeds up emulation by drawing fewer animation frames per second (fps), as is automatically done to optimize modern PC games. These days, frameskip isn't quite as critical a feature as it used to be because your CPU is more likely to be the limiting factor than your GPU, and there's no way to "skip" main-processor calculations. If you're running emulators on a relatively low-powered PC, however, tweaking your frameskip settings may help make a game more playable.

Plug-ins are used in many newer emulators for 3D consoles built around a plug-in architecture. This is a somewhat misleading way of saying that the graphics, sound, I/O processing, and so on are all modular, and various contributors can update them individually without having to sandwich new code into the heart of the emulator. At this point, only PlayStation emulation will require you to track down plug-ins from more than one source, and we'll help you pick out the right ones.

Mario games get a lot easier if you use save states.Save states are RAM snapshots of the game console being emulated. Usually, console games let you save your progress only at predetermined in-game save points (if at all). Emulators that allow you to save states basically let you bookmark your progress whenever you like.

Upscaling refers to a set of cleverly designed 2D-video-processing routines that permit older consoles, which commonly ran at resolutions in the vicinity of 200 by 200 pixels, to display natural-looking, higher-resolution images when emulated. Although some gaming purists prefer simply to multiply the original display size, thereby producing super-chunky pixels, upscaling can produce genuinely gorgeous results. For more technical details, read this Wikipedia article.

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